1. Technical Field
The disclosed embodiments generally relate to systems and methods for providing compression therapy. More particularly, the disclosed embodiments relate to systems and methods for applying intermittent compression to portions of a body part.
2. Background
Diseases such as lymphedema and venous insufficiency can often result in the pooling of bodily fluids in areas of the body distal from the heart. Venous insufficiency can result when the superficial veins of an extremity empty into the deep veins of the lower leg. Normally, the contractions of the calf muscles act as a pump, moving blood into the popliteal vein, the outflow vessel. Failure of this pumping action can occur as a result of muscle weakness, overall chamber size reduction, valvular incompetence and/or outflow obstruction. Each of these conditions can lead to venous stasis and hypertension in the affected area.
Fluid accumulation can be painful and debilitating if not treated. Fluid accumulation can reduce oxygen transport, interfere with wound healing, provide a medium that support infections or even result in the loss of a limb if left untreated.
Compression pumps are often used in the treatment of venous insufficiency by moving the accumulated bodily fluids. Such pumps typically include an air compressor, an appliance, such as a sleeve that is fitted over a problem area, and control circuitry governing mechanical components that cause the appliance to inflate and exhaust in a predetermined manner. The appliance typically includes a plurality of cells. Each cell can be independently inflated. The cells are typically arranged in a linear fashion along the limb and are inflated sequentially to promote the movement of fluid from the distal portion of the extremity toward the body core. This fluid movement serves to relieve pain and pressure associated with the edema. Exemplary devices are shown in U.S. Pat. No. 6,494,852 to Barak et al and U.S. Pat. No. 6,315,745 to Kloecker, each of which is incorporated herein by reference in its entirety.
In order to inflate the cells of the appliance, a compression pump typically includes a plurality of ports. Each port is connected to a cell of the appliance via a tube. Each port is capable of inflating the corresponding cell to a predetermined pressure, maintaining the cell at the predetermined pressure for a period of time and then reducing the pressure in the cell until atmospheric pressure is achieved. This process of inflating, maintaining pressure and reducing pressure can require a plurality of solenoid controlled valves to direct air flow and a separate mechanism to accurately control cell pressure, such as a pressure regulation device (i.e., a regulator).
Valves and regulators can be costly items. As such, minimizing the number of such valves and regulators in the system can significantly reduce both the complexity and the cost of a pneumatic compression device.
Conventionally, pneumatic compression devices use compression pumps and pressure regulators to control pressures at a plurality of ports. FIG. 1 depicts a conventional pneumatic compression device. As shown in FIG. 1, the arrows symbolize the direction of air flow through the device. In such devices, the compression pump 105 is configured to supply pressurized fluid, such as pressurized air, via a plurality of conduits to a plurality of pressure regulators 110a-N. The pressure regulators 110a-N are used to reduce the pressure of the pressurized fluid to a lower pressure based on a mechanical setting of each regulator 110a-N. A valve 115a-N corresponding to each regulator 110a-N can switchably connect a cell port to the corresponding regulator (i.e., the fluid at the regulated pressure) or the atmosphere (i.e., atmospheric pressure) as directed by a control processor 120. Typically, one control processor 120 can be used to control all valves 115a-N.
In operation, a first valve, such as 115a, for a particular cell port can be connected to a first regulator 110a. Switching the first valve 115a to be connected to the first regulator 110a can cause the fluid at the regulated pressure of the first regulator to inflate the cell port. The first regulator 110a can maintain the regulated pressure at the cell port as long as the valve 115a enables a connection between the first regulator and the cell port. For deflation, the first valve 115a can be closed to divert the pressurized fluid in the cell to the atmosphere. Other valves and their corresponding regulators operate in a substantially similar manner.
The pneumatic compression device shown in FIG. 1 is configured to enable each cell to be inflated and exhausted independently from every other cell. To do this, the pneumatic compression device of FIG. 1 requires a regulator 110a-N for each cell port. Moreover, because the regulators 110a-N are mechanical devices, the control processor 120 cannot directly set the pressure of the fluid. Rather, a user or care provider is typically responsible for ensuring that each regulator 110a-N is adjusted to provide pressurized fluid at an appropriate pressure.
Improved systems and methods for implementing and controlling a pneumatic compression device would be desirable.